To thank his students for helping with his research, Dr. Banon gives them the keys to his island cabin for the weekend. Before you start thinking beaches, the film takes place in Michigan in the middle of winter, so think ice, snow, and freezing temperatures. After class most of the kids take a school van and one kids car out to the island. Not sure why they take the extra car other than for plot convenience as there is plenty of room in the van.
Shortly after they get there, they break into different groups either to make out or sit by the bonfire. It's pretty fun until a mystery killer wearing a parka walks out of the woods and starts picking them off. In fact, most of them are dead within several minutes.
The next day the rest of the class arrives, but can only find Mark and he has no idea where anyone else has gone. On the way there, Nicole spotted Derek's car sitting by the side of the road. She heads back to see if anyone is there and finds Steve who is freaked out because Derek is dead.
By the time they get back to the cabin, two more friends are dead. Immediately suspicion falls on Mark as no one knows where he is, and everyone who came with him is missing. After a long discussion, they come to the conclusion that they should leave, but by that time both vans tires are flat.
Again the killer in the parka steps out of nowhere. Mark ends up rescuing Steve as the killer has injured him, and they barricade themselves in the cabin to wait for morning. With Nicole being a black belt in jujisu, you'd think that was some type of foreshadowing for some ass kicking. Nope. She's completely useless and flails around in the snow when the killer shows up. The ending has several twists.
There is ridiculous dialogue where Mark comes back to the cabin and instead of telling him their friends have been killed upstairs, they say "go look upstairs, Mark." Wouldn't it be natural to warn him so that he doesn't have to see that instead of discovering their bodies by sending him upstairs?
Also if everyone in a class has the same nightmare about going to the island and dying, wouldn't you decide to maybe not go to the island at all? And if you did go, and it looked exactly like in your dream, wouldn't your intution tell you that this was a bad idea and you needed to leave?